Ancient host-pathogen associations maintained by specificity of chemotaxis and antibiosis
Ancient host-pathogen associations maintained by specificity of chemotaxis and antibiosis
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DOI：
10.1371/journal.pbio.0040235
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发表时间：
2006-08-01
期刊：
影响因子：
9.8
通讯作者：
Mueller, Ulrich G.
中科院分区：
文献类型：
--
作者：
Gerardo, Nicole M.;Jacobs, Sarah R.;Mueller, Ulrich G.
寄生虫转换到新的宿主对生态和进化疾病动力学有深远的影响。转换需要寄生虫能够与新的宿主建立联系，并克服宿主的防御。对于大多数宿主寄生虫协会，目前还不清楚是什么特定的机制，防止感染的新主机。在这里，我们表明，寄生真菌种属Escovopsis，攻击和消耗真菌生长的蚂蚁培养的真菌，吸引到他们的主机通过趋化性。该反应是宿主特异性的：拟刺蛾属（Escovopsis spp.）对它们的自然宿主品种的生长比对其他密切相关的真菌更快。此外，培养的真菌分泌可以抑制Escovopsis生长的化合物。这些抗生素防御同样是特异性的：在大多数相互作用中，栽培品种可以抑制Escovopsis spp的生长。不知道在自然界中感染它们，但不能抑制它们的自然感染病原体的分离物。其中品种对新Escovopsis易感的情况仅限于一组狭窄的宿主-寄生虫菌株组合。因此，有针对性的趋化性和抗生素反应解释了为什么Escovopsis病原体不容易切换到新的主机，从而限制了长期的动态主机寄生虫共同进化在这个古老的协会。
Switching by parasites to novel hosts has profound effects on ecological and evolutionary disease dynamics. Switching requires that parasites are able to establish contact with novel hosts and to overcome host defenses. For most host parasite associations, it is unclear as to what specific mechanisms prevent infection of novel hosts. Here, we show that parasitic fungal species in the genus Escovopsis, which attack and consume the fungi cultivated by fungus-growing ants, are attracted to their hosts via chemotaxis. This response is host-specific: Escovopsis spp. grow towards their natural host cultivars more rapidly than towards other closely related fungi. Moreover, the cultivated fungi secrete compounds that can suppress Escovopsis growth. These antibiotic defenses are likewise specific: in most interactions, cultivars can inhibit growth of Escovopsis spp. not known to infect them in nature but cannot inhibit isolates of their naturally infecting pathogens. Cases in which cultivars are susceptible to novel Escovopsis are limited to a narrow set of host-parasite strain combinations. Targeted chemotactic and antibiotic responses therefore explain why Escovopsis pathogens do not readily switch to novel hosts, consequently constraining long-term dynamics of host-parasite coevolution within this ancient association.